using System.Collections.Generic;

namespace Ink
{
	public partial class InkParser
	{
		// Handles both newline and endOfFile
		protected object EndOfLine()
		{
            return OneOf(Newline, EndOfFile);
		}

        // Allow whitespace before the actual newline
        protected object Newline()
        {
            Whitespace();

            bool gotNewline = ParseNewline () != null;

            // Optional \r, definite \n to support Windows (\r\n) and Mac/Unix (\n)

            if( !gotNewline ) {
                return null;
            } else {
                return ParseSuccess;
            }
        }

		protected object EndOfFile()
		{
			Whitespace();

            if (!endOfInput)
                return null;

            return ParseSuccess;
		}


		// General purpose space, returns N-count newlines (fails if no newlines)
		protected object MultilineWhitespace()
		{
            List<object> newlines = OneOrMore(Newline);
            if (newlines == null)
                return null;

			// Use content field of Token to say how many newlines there were
			// (in most circumstances it's unimportant)
			int numNewlines = newlines.Count;
			if (numNewlines >= 1) {
                return ParseSuccess;
			} else {
                return null;
			}
		}

		protected object Whitespace()
		{
			if( ParseCharactersFromCharSet(_inlineWhitespaceChars) != null ) {
				return ParseSuccess;
			}

			return null;
		}

        protected ParseRule Spaced(ParseRule rule)
        {
            return () => {

                Whitespace ();

                var result = ParseObject(rule);
                if (result == null) {
                    return null;
                }

                Whitespace ();

                return result;
            };
        }

        protected object AnyWhitespace ()
        {
            bool anyWhitespace = false;
            while (OneOf (Whitespace, MultilineWhitespace) != null) {
                anyWhitespace = true;
            }
            return anyWhitespace ? ParseSuccess : null;
        }

        protected ParseRule MultiSpaced (ParseRule rule)
        {
            return () => {

                AnyWhitespace ();

                var result = ParseObject (rule);
                if (result == null) {
                    return null;
                }

                AnyWhitespace ();

                return result;
            };
        }

		private CharacterSet _inlineWhitespaceChars = new CharacterSet(" \t");
	}
}